Such a theft preventive apparatus is used as attached to an object of theft prevention such as a commodity displayed in a shop, for example, and outputs an alarm when the theft preventive apparatus is unlawfully detached from the object of theft prevention, i.e. when the theft preventive apparatus, with the alarm output device in operative state, is forcibly detached from the theft preventive apparatus.
There are various types of attached state detecting devices used according to forms of object of theft preventions to which the theft preventive apparatus are attached. For example, one type has a switch provided on a box to be retractable through contact with an object of theft prevention. A wire-like member may be connected to a box to act also as a element for attachment to an object of theft prevention to be wound around the object of theft prevention. A pin-like member may be used to extend into an object of theft prevention to hold it with a box.
In the ease of the above-mentioned attached state detecting device comprising a switch, the on/off state of the switch changes when the box of the theft preventive device is forcibly detached from the object of theft prevention. In the ease of the wire-like or pin-like attached state detecting device, the box is detached from the object of theft prevention by cutting the wire-like attached state detecting device or pulling out the pin-like attached state detecting device, bring about a change of state.
The alarm output device outputs an alarm based on information on the change of state of the attached state detecting device. Generally, the theft prevention device itself has a buzzer for sounding an alarm, or outputs an electric wave signal as the output of alarm, which electric wave signal is received to give an alarm sound.
A power source for driving the alarm output device in a box, generally, comprises an alarm output device driving battery mounted in the box in order to achieve compactness of the theft prevention device as a whole.
It is therefore necessary for the box to have also a built-in device for turning on and off the power supply the battery to the alarm output device.
A construction conventionally conceived as means for turning the power supply on and off is such that the supply is turned on and off based on whether or not to connect electrode terminals for contacting opposite poles of the battery.
With such a construction, however, the battery could move, by vibration during transport of the theft preventive apparatus, into contact with the electrode terminals, whereby power is supplied to the alarm output device to start its operation and consume the power of the battery. Furthermore, depending on a state of the attached state detecting device, the attached state detecting device may output an alarm. Thus, improvement has been desired.
The present invention has been made having regard to the state of the art noted above, and its object is to provide a theft preventive apparatus in which, in a condition not intended for use, does not start operating inadvertently by vibration or the like.